Starting circuit for gaseous discharge devices



1948. PQ'W. STUTSMAN I 27144-61199 STARTING CIRCUIT FOR GASEOUSDISCHARGE DEVICES Filed March 27, 1946 /NVENTOR PAUL WSTUTSMAN PatentedAug. 3, 1948 Application. March. 2,7, 1946,, Serial; 657,423.

This invention relates to gaseous electricaldischargedevices of the typehaving thermionic cathodes, and more. paliti'cularly to means wherebysuch discharge devices may be quickly started from a commercialsupplyline, of 110 volts.

In gaseous discharge devices of certain types, heating current. issupplied tothe cathodes only during the initial starting period. Inorder to disconnect the heatingcurrent after firing the tube, variousexpedients have been used, Time delay' relays or bi-metallic jthermalstrips have beeni associateduwith the heating circui-tjs; but theseinvolvemovable contact points which deteriorate in a short time, andfurthermore they do not insure that the heating current will bediscontinued immediately upon the firing of the device. Also, heavyresistors may be interposed in the heating current circuit. However,these tend to limit the heating current during the starting period aswell as after the tube has fired.

It is among the objects of the present invention to provide a circuitarrangement for gaseous discharge devices in which the cathode israpidly heated on starting and in which the heating current isimmediately discontinued upon the firing of the device.

The above and other objects and features of iris aisoQprovidediw astarting electmde of the type adaH-tledi Q establ glow discharge" withthe cathode l5! Thestarting electrode 16" is connectedflto the plate. ofthe tube [2f through a relatively large, resistor Ll; whichmay be; ofthe,

order. 0f 100,000 ohms. a A In, the operationof, the circuit describedi'n the, foregoing; when the terminals, 6 and If are con! nected to; acommercial?suiipl fline by the closures of: a suitable switch, thestarting, electrode lid of, th tube la and: the main-, anod'e l'3tareinitially at substantially the same potential; relative to the.

hode 51 Howe erLwhen a. ow i fa eis establishedbetween the startinelectrode t6 and the cathode [5, the potential of the electrode I6 issubstantially reduced as compared with the potential at the anode I 3,due to the current flow through the resistor I1. initiates a dischargebetween the anode l3 and the cathode l5, and a heavy flow of currentthrough the cathode-anode circuit of the tube is effected. This currentflows through the thermionic cathode 9 of thetube 4 and the condenserthe invention will be made fully apparent to those skilled in the artfrom a consideration of the following detailed description taken inconjunction with the accompanying drawing which shows a diagrammaticillustration of an electrical circuit embodying the present invention.

Referring to the drawing, reference numeral 4 indicates a gaseousdischarge device including an anode 5 adapted to be connected to one ofthe terminals 6 of a commercial supply line through a resistor 8 whichmay be of the order of 100 ohms. The discharge device 4 is also providedwith a thermionically emissive cathode 9 which is connected to the otherterminal 1 of the power supply line through a load resistance In whichmay be of the order of 2500 ohms. A condenser H of relatively largecapacity is shunted across the resistance load It]. In order to supplyheating current to the cathode 9, one terminal of the filament circuitis connected to the terminal 6 through a trigger tube l2. The tube l2includes an anode I 3 connected through a small resistor l4, which mayof the order of six ohms, to the supply line leading to the anode 5, ata point between the terminal 6 and the resistor 8, The cathode I5 of thetube I2 is connected to one side of the filament 9 and through thisfilament to the resistance load I0 and condenser l l. The tube II. Theheavy flow of heating current through the thermionic cathode 9 rapidlyheats thiscathode to such a temperature that the tube 4 fires,permitting the flow of current from the line 6-! through the load In.Upon the firing of the tube 4. the potential drop across this tubebecomes relatively small, and the tube I2 is extinguished. Thereafterthe cathode 9 is heated by ionic bombardment sufliciently to maintainthermionic emission, and thereby maintain the discharge throughsuccessive cycles.

The circuit described in the foregoing insures that an ample heatingcurrent will initially flow through the thermionic cathode 9 sufficientto heat this cathode rapidly and insure a prompt discharge through thetube 4. Upon the firing of the tube 4, the circuit insures that theheating current to the cathode 9 will be instantly discontinued.

While there has been herein described a preferred embodiment of theinvention, other embodiments within the scope of the appended claimswill be apparent to those skilled in the art from a consideration of theform shown and teachings herein.

What is claimed is:

1. A circuit for initiating an arc in a gas discharge device of the typeincluding an anode and a heated cathode comprising a source of currentconnected across and adapted to supply operating potential to saiddevice, a tube of the type having relatively low voltage startingcharacter- The glow discharge 3 istics, the anode of said tube beingconnected to the anode of said discharge device and to one terminal ofsaid source, and the cathode of said tube being connected through theheating circuit of the cathode of said discharge device to the oppositeterminal of said source, a resistance load connected in the dischargecircuit of said device,

and a capacitor in'shuntwith said load.

2. A circuit for initiating an arc in a gas discharge device of the typeincluding an anode and a heated cathode comprising a current sourceconnected across and adapted to supply operating potential to saiddevice, a tube of the type in which a glow discharge initiates an arcdischarge. through the anode-cathode circuit thereof, the, anode of saidtube being connected to the anode-:

ing potential to said device, a tube of the type having a pair ofelectrodes between which a of said discharge device and to one terminalof v said source, and the cathode of said tube being- "i i-and thecathode of said tube being connected connected through the heatingcircuit of the cathode of said discharge device to the opposite terminalof said source, aresistance load con-e nected in the discharge circuitof said device, and

a capacitor in shunt with said load.

3. Aci'rcuit for initiating an arc in .a gasvdis-f charge device of thetype including an anode and a heated cathode comprising a current sourceconnected across and adapted to supply operating potential to saiddevice, a tube of the type having a pair of electrodes between ,which aglow discharge occurs upon the application of a potential thereto forinitiating an arc discharge through discharge device and to oneterminal, of .said

glow discharge occurs upon the application of a relatively low potentialthereto for initiating a tsubstantially larger current flow through theanpr de-cathode circuit thereof, the anode of said tube being connectedto the anode of said discharge device and to one terminal of saidsource,

through the heating circuit of the cathode of said discharge device tothe opposite terminal of said source, and a resistance load connected inthe.

discharge circuit of. said device. 1

,PAUL w. s'rorrsMAu REFERENCES, CI'IIED,

The following references are ofrecord in the Number I Spencer July 21,1936 Peters, Aug; 20, 1940

